Conditional Selection of Rows Using TSQL SQL Server (2008 R2) - sql

Question

I've been staring at this for hours and hours and can't come up with an "elegant" set-based way of getting the result set I need...
Here's my sample data (my real data could be 1,000,000+ rows)...
DECLARE #t AS TABLE (ID int,ID1 nvarchar(15),[DATE] date,PERIOD int,[TYPE] nchar(1));
INSERT INTO #t (ID,ID1,[DATE],PERIOD,[TYPE])
VALUES
(1,N'NUM1','2016-01-01',1,N'B'),
(2,N'NUM1','2016-01-01',2,N'A'),
(3,N'NUM1','2016-01-01',3,N'A'),
(4,N'NUM1','2016-01-01',4,N'B'),
(5,N'NUM1','2016-01-01',4,N'A'),
(6,N'NUM1','2016-01-01',5,N'A'),
(7,N'NUM1','2016-01-02',1,N'A'),
(8,N'NUM1','2016-01-02',2,N'A'),
(9,N'NUM1','2016-01-02',3,N'A'),
(10,N'NUM1','2016-01-02',4,N'A'),
(11,N'NUM1','2016-01-02',5,N'A'),
(12,N'NUM2','2016-01-01',1,N'A'),
(13,N'NUM2','2016-01-01',1,N'B'),
(14,N'NUM2','2016-01-01',2,N'A'),
(15,N'NUM2','2016-01-01',3,N'A'),
(16,N'NUM2','2016-01-01',4,N'B'),
(17,N'NUM2','2016-01-01',4,N'A'),
(18,N'NUM2','2016-01-01',5,N'A'),
(19,N'NUM2','2016-01-02',1,N'A'),
(20,N'NUM2','2016-01-02',2,N'B'),
(21,N'NUM2','2016-01-02',3,N'A'),
(22,N'NUM2','2016-01-02',4,N'A'),
(23,N'NUM2','2016-01-02',4,N'B'),
(24,N'NUM2','2016-01-02',5,N'A');
Here is the result set I'm trying to get...
1,'NUM1','2016-01-01',1,'B'
2,'NUM1','2016-01-01',2,'A'
3,'NUM1','2016-01-01',3,'A'
5,'NUM1','2016-01-01',4,'A'
6,'NUM1','2016-01-01',5,'A'
7,'NUM1','2016-01-02',1,'A'
8,'NUM1','2016-01-02',2,'A'
9,'NUM1','2016-01-02',3,'A'
10,'NUM1','2016-01-02',4,'A'
11,'NUM1','2016-01-02',5,'A'
12,'NUM2','2016-01-01',1,'A'
14,'NUM2','2016-01-01',2,'A'
15,'NUM2','2016-01-01',3,'A'
17,'NUM2','2016-01-01',4,'A'
18,'NUM2','2016-01-01',5,'A'
19,'NUM2','2016-01-02',1,'A'
20,'NUM2','2016-01-02',2,'B'
21,'NUM2','2016-01-02',3,'A'
22,'NUM2','2016-01-02',4,'A'
24,'NUM2','2016-01-02',5,'A'
Simply put, each day has 5 periods. They can be of type A or B. I need to get the A types. but if there are no A types, I need to get the B types... (Sounds so simple when I write it out.., but my brain will not come up with something suitable)
Pleeeeeease put me out of my misery..

Answer 1

You can use ROW_NUMBER for this:
SELECT ID, ID1, [DATE], PERIOD, [TYPE]
FROM (
SELECT ID, ID1, [DATE], PERIOD, [TYPE],
ROW_NUMBER() OVER (PARTITION BY ID1, [DATE], PERIOD
ORDER BY [TYPE]) AS rn
FROM #t) AS t
WHERE t.rn = 1
Using ORDER BY [TYPE] in the OVER clause of ROW_NUMBER places 'A' records on top of 'B' records. If there are no 'A' records for a given ID1, [DATE], PERIOD then B records are assigned rn = 1.

Answer 2

Your desired outpout contradicts the statement that "I need to get the A types. but if there are no A types, I need to get the B types... ". Every date in the data has one or more 'A' types. By the statement, the output should include only the 'A' types. But if the statement is correct, then this should work:
Select d.[DATE], t.Id, t.ID1, t.PERIOD, t.[TYPE]
from (select distinct [date] from #t) d
left join #t t
on t.[date] = d.[date]
and t.type = case when exists
(select * from #t
where [date] = d.[Date]
and type = 'A') then 'A'
else 'B' End

Answer 3

I've just come up with
SELECT * FROM #t WHERE [TYPE]='A'
UNION ALL
SELECT * FROM #t t1 WHERE [TYPE]='B' AND NOT EXISTS (SELECT ID FROM #t WHERE ID1=t1.ID1 AND [TYPE]='A' AND [DATE]=t1.[DATE] AND Period=t1.Period)
ORDER BY ID;
which give's me what I need...